PGM Purification via Carbonyl Halide Decomposition
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Solution Overview
Problem
Current methods are uncertain and inefficient for separating and purifying platinum group metals (PGMs) from mixtures containing multiple PGMs and other metals, as they often require high temperatures and are not effective in decomposing volatile complexes formed with carbon monoxide, especially when non-PGMs like Ni, Co, Fe, Cr, Mo, and W are present.
Innovation Solution
A process involving the formation of anhydrous PGM halides, treatment with carbon monoxide at specific temperatures and pressures to produce PGM carbonyl halides, followed by thermal decomposition at effective temperatures to separate and purify platinum, rhodium, palladium, and iridium metals, using a reactor system with a metallic surface as a chlorine scavenger to enhance decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal decomposition is used to separate PGMs from mixtures, then purification is achieved, but high temperatures are required and non-PGM metals interfere with the process
Solution Approach 1:
The invention changes the chemical parameters by forming volatile carbonyl halide complexes through reaction with carbon monoxide and halogens at moderate temperatures (50-200°C), then decomposes these complexes at controlled temperatures to achieve separation. This avoids the need for high temperature thermal decomposition of the original metal mixtures.
Solution Approach 2:
The invention uses volatile carbonyl halide complexes as intermediary compounds to separate PGMs from non-PGM metals. These intermediaries form selectively with PGMs at moderate temperatures and can be decomposed controllably, allowing separation without direct high-temperature processing of the original mixture.
2Manufacturing precision
If volatile complexes are formed for separation, then selectivity improves, but uncertainty remains when multiple PGMs and non-PGMs are present
Solution Approach 1:
The invention applies local quality by exploiting the different volatility and decomposition characteristics of carbonyl halide complexes formed by different metals. Each PGM forms a complex with specific properties that allow selective decomposition at controlled temperatures, enabling reliable separation even in complex mixtures containing multiple PGMs and non-PGM metals.
3Productivity
If carbon monoxide treatment is used to form complexes, then PGM extraction is enabled, but reaction completeness is insufficient
Solution Approach 1:
The invention optimizes reaction parameters by using specific halogen sources (halogens or metal halides) in addition to carbon monoxide, and by controlling temperature (50-200°C) and time to ensure complete complex formation. This enhances both extraction efficiency and reaction completeness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process effectively separates and purifies PGMs, achieving high yields of platinum and rhodium metals while minimizing contamination from other metals, particularly relevant in recycling PGMs from catalysts like vehicle exhaust converters.
Implementation Method 1
treating said PGM halide with carbon monoxide at an effective temperature, pressure and time to form said PGM carbonyl halide
Implementation Method 2
heating said platinum carbonyl halide at an effective platinum decomposition temperature to produce said purified platinum
Implementation Method 3
using a reactor system with a metallic surface as a chlorine scavenger to enhance decomposition
Data Source
AI summary
A process for the production of a purified PGM selected from the group consisting of platinum and rhodium from an impure PGM source, the process comprising (a) obtaining an anhydrous PGM halide from the impure PGM source; (b) treating the PGM halide with carbon monoxide at an effective temperature; pressure and time to form the PGM carbonyl halide; and (c) (i) wherein the PGM is platinum, heating the platinum carbonyl halide at an effective platinum decomposition temperature to produce the purified platinum; (ii) wherein the PGM is rhodium, heating the rhodium halide at an effective rhodium decomposition temperature to produce the purified rhodium; and (iii) wherein the platinum carbonyl carbonyl halide and the rhodium carbonyl halide are in a gaseous mixture, effecting step (i) at a temperature lower than the rhodium effective decomposition temperature prior to effecting step (ii). The process is of particular value in the recovery and recycle of PGM materials from vehicle exhaust catalytic converters.